Preheat oven to 325F.,Line mini muffin tins with paper liners.,Whisk together flour, baking soda, baking powder, salt, and cardamom.,In a large bowl, combine dates with the boiling water and butter.,Stir until butter is melted and dates are soft, about 2 minutes.,Stir in brown sugar, beaten egg, and vanilla.,Add flour mixture, and stir just until combined.,Stir in walnuts.,Divide batter evenly among lined cups, filling each three-quarters full.,Bake, rotating tins halfway through, until a cake tester inserted in centers comes out clean, about 15 minutes.,Transfer tins to wire racks to cool completely before removing cupcakes.,Cupcakes can be stored overnight at room temperature, or frozen up to 1 month, in airtight containers.,______,Serve immediately.